Plastics in Electric Vehicles: Where Engineering Compounds Go

Electric car sales grew by about 20% in 2025 to more than 20 million, roughly one in four new cars sold worldwide, according to the IEA. Its forecast for 2026 is 23 million. For a Tier-1 or Tier-2 moulder in Thailand, Mexico or Türkiye, that growth arrives as new part numbers with briefs that read differently from the ICE parts they replace.

This note maps where plastics in electric vehicles actually go, what each part has to survive, and which of our compound families we would start from.

What changes when the powertrain goes electric

Voltage. Many traction systems run at around 400 V, and 800 V platforms such as Hyundai's E-GMP, announced in 2020 with both 400 V and 800 V charging, are now in series production. Anything that holds or separates high-voltage conductors now needs a stated tracking index (CTI), adequate creepage and clearance, and stable insulation after heat ageing.

Fire. Thermal runaway in a cell is the failure everyone designs around. China's revised traction battery standard, GB 38031-2025, applies from 1 July 2026 and requires that a thermal runaway event leads to no fire or explosion over a two-hour observation period. Plastics close to the cells need a flame rating, and often more than that.

Heat. The exhaust manifold is gone, but cells, power electronics and fast charging all generate heat, and most of it is carried away by a water-glycol coolant loop.

Weight. The battery is heavy, so every other kilogram is under scrutiny. The American Chemistry Council puts plastics and polymer composites at about 50% of a vehicle's volume but only around 10% of its weight.

Colour. High-voltage parts are conventionally orange, so FR compounds have to be colour-matched as well as rated.

Part-by-part map

Battery enclosures and trays

Large battery trays are often metal or thermoset, but covers, module housings and internal carriers are prime territory for glass-filled polyamide. The requirements stack up: stiffness without creep under clamping loads, impact resistance, low warpage over a big footprint, and a flame rating at the moulded wall thickness. OSAMIDE covers PA6 and PA66 with glass fibre up to 65 to 70% and FR on request. For the metal-replacement logic behind these parts, see glass-filled polyamide for metal replacement.

Connectors, busbars and the CTI question

At 800 V, a connector body is an insulation system. Two numbers dominate. The UL 94 rating, at the thinnest wall, covers flame. CTI governs how close conductors can sit on the moulded surface: a PLC 0 material (600 V and above) lets the designer use shorter creepage distances than a lower-CTI material at the same voltage. Our note on UL 94, glow-wire and CTI covers the tests in detail.

Busbar holders add mechanical load. A bolted joint runs warm and stays clamped for years, so creep resistance at temperature matters as much as the electrical values. Semi-aromatic grades such as OSAMIDE RAG 7 and RAG 10 (PA6T/6I with 35% and 50% glass) are worth trialling where PA66 runs out of heat or stiffness; see our PPA and PA6T explainer. PBT from OSABATE, such as 506 GF with 30% glass, is the other common route for connector bodies thanks to its low moisture uptake and stable dimensions.

Charging inlets

The inlet on the car body lives outdoors, takes knocks from the charging handle and has to keep pins exactly aligned. That points to impact-modified blends with good weathering. OSAALLOY CP 1180 is an impact-modified PC/PBT; glass-filled PBT is the alternative where stiffness and pin positioning lead the brief. Specify the UV exposure, the flame rating and the colour together, because each affects the other.

Thermal management

Coolant connectors, quick connectors and pump or valve housings sit in water-glycol at elevated temperature for the life of the car. Heat-stabilised PA66 with glass fibre is the usual starting point, with PA6T/6I where temperature or dimensional stability needs more margin. Ask for glycol-ageing data at your operating temperature rather than relying on a general claim; it is the property that separates grades here.

Housings and lightweighting

On-board chargers, DC-DC converters and home wallboxes need FR housings that mould thin and take an impact. OSAALLOY CP 6080, an impact-modified PC/ABS with UV stabilisation and good flow, and FR grades of OSANATE PC fit this brief. For brackets and carriers where weight matters, carbon-fibre PA66 (OSAMIDE AISC grades, 15 to 50% CF) offers stiffness at lower density than high-glass grades.

How we approach an EV brief

Automotive is our largest market, at 42% of revenue, and OEM qualifications have been part of our work since our Jhajjar plant was commissioned in 2019. For EV parts we start from the families above, add FR, UV or colour as the part demands, and colour-match high-voltage orange to your reference using spectrophotometry in our lab. Glow-wire screening is in-house; UL 94 and other certified tests are arranged through external labs on request. Browse the material finder or see our applications page for other automotive parts.

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